Flow switch



G. M. EULER April 3, 1956 FLOW SWITCH Filed July 24, 1953 Inventor: George M. EufeT,

His Attorneg.

United States Patent f FLOW SWITCH George M. Euler, Morrison, Ill., assignor to General Electric Company, a corporation of New York Application July 24, 1953, Serial No. 370,982

Claims. (Cl. zoo-81.9

This invention relates to fluid flow responsive devices, and more particularly to an improved flow switch in which mechanical movement is transmitted from an enclosed fluid under pressure to a different medium.

The general function of flow switches is to make or break an electric circuit in response to deviations from a predetermined level in the rate of flow of a fluid. There are several difficulties inherent in the use of such a switch. One of the most important lies in the fact that it is necessary to have the flow of fluid operate the switch, and yet it often becomes essential to protect the operating elements of the switch from the various corrosive properties that the fluid may have. Thus, the desirable goal is to obtain a completely leakproof seal between the fluid and the operating parts of the switch without sacrificing the ease of operation of the switch and without having the switch be appreciably affected by static pressure changes in the fluid.

An object of this invention is, therefore, to provide an improved flow switch having an excellent seal between the fluid and the switch mechanism without sacrificing any of the operating qualities of the switch.

Another object of this invention is to achieve a switch which will have the desired sensitivity to fluid flow with appreciably no response to changes in the static pressure of the fluid.

Further objects and advantages of this invention will become apparent and the invention will be better understood by reference to the following description and the accompanying drawing, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a side view of the switch and the pipe containing the flowing fluid, all but the lower left-hand quarter being in cross-section;

Fig. 2 is a sectional view of Fig. 1 looking in the direction of arrows 22; and

Fig. 3 is an exploded view in perspective-of the elements operating to transmit mechanical movement from the enclosed medium and of the seal.

Referring now to the drawing, there is shown a pipe section 1 through which the fluid under pressure flows in the direction of arrow 1a. The top of pipe section 1 is modified, as at 2, to accommodate a frame 3, secured to pipe 1 by screws 4. An opening or aperture 5 is provided in frame 3 and pipe 1 to accommodate the vertical member 6 of an operating lever 7 (shown in Fig. 3).

Vertical member 6 is provided with two knife edge slots 8 (Figs. 2 and 3); and stationary pivot plate 9, composed of semicircular parts 9a and 9b, coacts with slots 8 to permit pivoting of lever 7 about pivot plate 9. Helical spring 10 is under compression between side 11 of lever 7 and stationary cap 12. The position of cap 12 is adjustable by nut 13 on partly threaded member 14 which is secured to frame 3. A hole 15 (Fig. 3) is provided in side 11 of the lever so that member 14 will not interfere with movement of lever 7.

2,740,858 Patented Apr. 3, 1956 Attached to frame 3 by screws 16 is a snap action switch 17. Snap action switch 17 contains a pair of switch contacts (not shown) which may be of any wellknown standard construction. These contacts may be either normally opened or normally closed depending upon the particular function desired to be effected by the fluid flow in pipe 1. An actuating button 13 is positioned to be pushed upward by operating end 19 of lever 7 to force the contacts within casing 17 away from their biased normal position.

Pipe 1 is provided with a constriction or restriction 20; and the downstream side 21 thereof forms a seat for piston 22 which has, on the downstream side, a projection 23 either integral with or securely attached to it. This projection 23 abuts against a vertical jacket portion 24 of a flexible sealing member 25 (Fig. 3), formed of suitable material such as neoprene or buna. Sealing member 25 has a slot 26 extending within jacket 24 substantially the entire length thereof. Slot 26 accommodates vertical member 6 which extends down within slot 26 at least far enough to extend below protuberance 23. A flange-like gasket section 27 of seal 25 has a periphery coincident with the periphery of stationary pivot plate 9. This facilitates clamping of gasket 27 and pivot plate 9 by frame 3 in a recess 28 provided in pipe 1. This arrangement of the seal 25 within the recess 28 affords a tight leak-proof seal between the fluid under pressure and the operating parts of the switch. It is clear that pivot plate 9 is also protected by the seal, and that the knife edge pivoting action will not be affected by corrosion by the fiuid under pressure. This permits more accurate control by means of adjustable nut 13, and reduces to a negligible amount the force required for movement of lever 7.

The operation of the switch when a fluid under pressure is flowing through pipe 1 in direction In will now be described. Piston 22 seated upon seat 21 of restriction 20 blocks the fluid flow through pipe 1. To continue flowing, the fluid must force piston 22 away from its seat 21. At a predetermined level of flow, protuberance 23 on piston 22 will bear against jacket 24 of rubber seal 25, within which is vertical member 6 of lever 7. Further increase in flow will cause the force exerted by spring 10 to be overcome and member 6 to be pushed to the right, as shown in Fig. 1. Lever 7 pivots about stationary pivot plate 9 in a counterclockwise direction, causing end 19 of lever 7 to descend and remove pressure from button 18. Release of pressure on button 18 actuates the contacts inside snap switch 17 to accomplish the desired results in response to the increase over the predetermined level of fluid flow. The quantity of flow necessary to actuate the contacts is determined by the force with which spring 10 presses on end 11 of lever 7. The spring force may be adjusted to the desired value by means of nut 13 on threaded member 14.

Spring 10, lever mechanism 7, pivot plate 9, and the contacts inside casing 17 will all operate completely free from any danger from the fluid under pressure. Despite the fact that the lever is directly actuated by the piston, and that it extends into the path of the liquid, the rubber seal around it completely insulates it from the liquid, and the gasket of seal 25 in recess 28 between pivot'plate 9 and the fluid insures fluid-tight protection for the rest of the operating elements.

It is clear from the above description that my improvement achieves a switch mechanism easy of operation, free from undue friction, and yet completely-protected and insulated from the operating fluid.

While the invention has been explained by describing a particular embodiment thereof, it will be apparent that improvements and modifications may be made without departing from the scope of the invention as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A flow switch for actuation in response to departure from a pretermined rate of flow of a fluid under pressure in a pipe comprising contact means, lever means having a first portion with one end engaging said contact means and adapted to actuate the same, spring means engaging the other end of said first portion of said lever means and arranged to bias the same to a first position, said pipe having an aperture in its wall and a recess in said aperture, said lever means having a second portion depending from said first portion intermediate said ends thereof and extending through said aperture and said recess into said pipe, means within said pipe adapted to exert a force against said second portion thereby to move said first portion of lever means to a second position thereby actuating said contact means in response to a departure of said fluid flow from said predetermined rate, a pliable insulating member comprising a jacket completely covering said second portion of said lever means and having an opening adapted to receive said second portion, said insulating member further comprising a peripheral flange having one face in the same plane as said opening and integral with said jacket, said flange being positioned in said recess, a pivot plate positioned in said recess over said flange, said pivot plate having a slot formed therein accomodating said second portion of said lever means and forming a pivot therefore, and means clamping said pivot plate and said flange in said recess whereby said fluid is prevented by said insulating member from coming into contact with said second portion of said lever means and from leaking into said recess.

2. A flow switch for actuation in response to departure from a predetermined rate of flow of a fluid under pressure in a pipe comprising a pipe section, mounting means secured to said pipe section, switch means on said mounting means, lever means having a first portion with one end engaging said switch means and adapted to actuate the same, spring means on said mounting means engaging the other end of said first portion and normally biasing the same to a first position, said pipe section having a recess formed in its wall and an opening communicating between said recess and the interior of said pipe section, said lever means having a second portion depending from said first portion intermediate said ends thereof and extending through said recess and said opening into said pipe section, means within said pipe section adapted to exert a force against said second portion of said lever means to move said first portion of said lever means to a second position in response to a departure of said fluid flow from said predetermined rate thereby to actuate said switch means, a pliable insulating member comprising a jacket completely covering said second portion of said lever means and having a peripheral flange portion, said flange portion being position in said recess and closing said opening, and a pivot plate positioned in said recess over said flange portion, said pivot plate comprising two halves each having a slot formed therein, said slots co-operating to accomodate said second portion of said lever means, said second portion of said lever means having slots respectively formed in the edges thereof co-operating with said pivot plate slots thereby to pivot said lever means, said mounting means clamping said pivot plate and said flange portion in said recess whereby said fluid is prevented from coming in contact with said second portion of said lever means and from leaking through said opening.

3. A flow switch adapted for actuation in response to departure from a predetermined rate of a flow of a fluid under pressure in a pipe comprising contact means, lever means having a first portion with one end engaging said contact means and adapted to actuate the same, spring means engaging the other end of said first portion of said lever means and arranged to bias the same to a first position, said pipe having an aperture in its wall and a re cess in said aperture, said lever means having a second portion depending from said first portion intermediate said ends thereof and extending through said aperture and said recess into said pipe, said pipe having a restriction formed therein, a piston member seated in said restriction, the downstream side of said piston member engaging said second portion of said lever means thereby to move said first portion of said lever means to a second position to actuate said contact means in response to a departure of said fluid flow from said predetermined rate, a pliable insulating member comprising a jacket completely covering said second portion of said lever means and having an opening adapted to receive said second portion, said insulating member further comprising a peripheral flange having one face in the same plane as said opening and integral with said jacket, said flange being positioned in said recess, pivot means for said second portion of said lever means positioned in said recess over said flange, and means clamping said pivot means and said flange in said recess whereby said fluid is prevented by said insulating ember from coming into contact with said second portion of said lever means and from leaking into said recess.

4. A flow switch adapted for actuation in response to departure from a predetermined rate of flow of a fluid under pressure in a pipe comprising Contact means, lever means having a first portion with one end engaging said contact means and adapted to actuate the same, spring means engaging the other end of said first portion of said lever means and aranged to bias the same to a first position, said pipe having an aperture in its wall and a recess in said aperture, said lever means having a second portion depending from said first portion intermediate said ends thereof and extending through said aperture and said recess into said pipe, said pipe having a restriction formed therein, a piston member seated in said restriction, the downstream side of said piston member engaging said second portion of said lever means thereby to move said first portion of said lever means to a second position to actuate said contact means in response to a departure of said fluid flow from said predetermined rate, a pliable insulating member comprising a jacket completely covering said second portion of said lever means and having an opening adapted to receive said second portion, said insulating member further comprising a peripheral flange having one face in the same plane as said opening and integral with said jacket, said flange being positioned in said recess, a pivot plate positioned in said recess over said flange, said pivot plate having a slot formed therein to accommodate said second portion of said lever means and forming a pivot therefore, and means clamping said pivot plate and said flange in said recess whereby said fluid is prevented by said insulating member from coming into contact with said second section of said lever means and from leaking into said recess.

5. A flow switch adapted for actuation in response to departure from a predetermined rate of flow of a fluid under pressure in a pipe comprising a pipe section having its inlet and outlet in axial alignment, mounting means secured to said pipe section, switch means on said mounting means, lever means having a first portion with one end engaging said switch means and adapted to actuate the same, spring means on said mounting means engaging the other end of said first portion of said lever means and normally biasing the same to a first position, said pipe section having a recess formed in its wall and an opening communieating between said recess and the interior of said pipe section, said lever means having a second portion depending from said first portion intermediate said ends thereof extending through said recess and said opening into said pipe section, said pipe section having a restriction formed therein, piston member seated in said restriction, the downstream side of said piston member engaging said second portion of said lever means thereby to move said first portion of said lever means to a second position to actuate said switch in response to a departure of said fluid flow from said predetermined rate, a pliable insulating member comprising a jacket completely covering said second portion of said lever means and having a peripheral flange portion, said flange portion being positioned in said recess enclosing said opening, and a pivot plate positioned in said recess over said flange portion, said pivot plate comprising two halves each having a slot formed therein, such slots co-operating to accommodate said second portion of said lever means, said second portion of said lever means having slots respectively formed in the ledges thereof co-operating with said pivot plate slots thereby to pivot said lever means, said mounting means clamping said pivot plate and said flange portion in said recess whereby References (Jilted in the file of this patent UNITED STATES PATENTS 2,001,168 Turner May 14, 1935 2,119,783 Harrington June 7, 1938 2,244,373 Powers June 3, 1941 2,428,565 Guidosh Oct. 7, 1947 2,539,386 Albert Jan. 30, 1951 2,583,814 Burklin Ian. 29, 1952 FOREIGN PATENTS 195,794 Germany Feb. 25, 1908 

